N-secondary-alkyl alkylene diamine salts of phosphate ester acids

ABSTRACT

A COMPOSITION USEFUL AS A CORROSION AND SCALE INHIBITOR IS OBTAINED BY REACTING A N-SECONDARY ALKYL ALKYLENE DIAMINE (E.G. CONTAINS AN AVERAGE OF 8-20 CARBON ATOMS IN THE ALKYL GROUP AND ABOUT 2-4 CARBON ATOMS IN THE ALKYLENE GROUP) AND A PHOSPHATE ESTER, OBTAINED FOR EXAMPLE BY REACTING ABOUT EQUAL MOLAR AMOUNTS OF POLYPHOSPHORIC ACID AND A CONDENSATION PRODUCT OF AN ALIPHATIC PRIMARY ALCOHOL (PREFERABLY CONTAINS 3-6 CARBON ATOMS) AND AT LEAST ONE MOLE (PREFERABLY 1-10 MOLES) OF AN ALKYLENE OXIDE (PREFERABLY ETHYLENE OXIDE). FINAL REACTION PRODUCT CAN HAVE A PH OF 5-9.

United States Patent O 3,787,533 N-SECONDARY-ALKYL ALKYLENE DIAMINESALTS F PHOSPHATE ESTER AClDS Arthur Lee Larsen, Denver, Colo., assignorto Marathon Oil Company, Findlay Ohio No Drawing. Continuation-impart ofapplication Ser. No. 190,266, Oct. 18, 1971. This application Jan. 3,1972,

Ser. No. 215,094

Int. Cl. C02b 5/06; C0715 9/08 US. Cl. 260-924 13 Claims ABSTRACT OF THEDISCLOSURE CROSS REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part of copending application Ser. No. 190,266 filedOct. 18, 1971, which teaches the use of the compositions claimed in thisapplication.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to novel compositions useful as corrosion and scale inhibitors.The composition is a reaction product of a N-secondary alkyl alkylenediamine and a phosphate ester. These compositions are useful ascorrosion and scale inhibitors, etc.

Description of the prior art Corrosion control in the petroleum industryis obtained in general by changing the environment and/ or by forming aprotective barrier on the object being corroded. Corrosion inhibitorsare generally of the neutralizing type or the film-forming type.Neutralizing inhibitors function by neutralizing the active corrodantsin the system Whereas film-formers are believed to function by placing aprotective barrier between the metal and the corrosive environment.

Film-forming inhibitors used in greatest quantity in the oil industryinclude the fatty and heterocyclic nitrogencontaining compounds, such asthe amine-acid complexes and the imidazoline derivatives. In particular,fatty amines and particularly the diamines combined with fatty acidssuch as resin acids and tall oil acids, oxidized petroleum fractions andnaphthentic acids produce good film-forming corrosion inhibtors.

Applicant has discovered a composition which is useful, inter alia, as afilm-forming corrosion inhibitor, scale inhibitor, etc. The compositionis obtained by reacting a N-secondary-alkyl alkylene diamine and aphosphate ester.

DESCRIPTION OF THE INVENTION Examples of useful phosphate esters includethose found in US. Pat. No. 3,331,896 to Eiseman, Jr. et al. Preferredphosphate esters are obtained by reacting about equal molar amounts ofpolyphosphoric acid and the condensation product of an aliphatic primaryalcohol (contains 1 up to about 12 carbon atoms and preferably 3,787,533Patented Jan. 22, 1974 contains about 3 to about 6 or more carbon atoms)and at least about one mole, preferably about 1 to about 10 moles, of analkylene oxide (preferably containing about 2 to about 4 carbon atoms)such as ethylene oxide. The polyphosphoric acid is composed of anequilibrium mixture of orthophosphoric, pyrophosphoric, and higherlinear phosphoric acids. Commercially available polyphosphoric acidsrange from about. 110% to about 120% H PO and contain about to about86.5% P 0 A more detailed description of useful polyphosphoric acids isfound in U.S. 3,331,896 to Eiseman, Jr. et al. For purposes of thisinvention, one mole of polyphosphoric acid is defined as the equivalentof one mole of P 0 as defined in polyphosphoric acid.

Examples of N-secondary-alkyl alkylene diamines are found in US. Pat.No. 3,398,196 to Fuller, Jr. et a1. Particularly useful diamines areidentified by the formula:

wherein x and y are positive integers having a sum of about 6 to about30 and n is a positive integer within the range of about 2 to about 4and preferably is 3. The polyamines are preferably oleophilic andcontain substantially saturated alkyl chains. Additional examples ofuseful diamines include those found in Product Data Bulletin, BulletinNo. 68-3, under the title Beta Amines and Derivatives, Armour IndustrialChemicals, Box 1805, Chicago, 111. A particularly usefulN-secondaryalkyl alkylene diamine is one wherein the alkyl groupcontains an average of about 10 to about 20 aliphatic carbon atoms.

The diamine and the phosphate ester are reacted in sufficient amounts togive a resulting pH of about 5 to about 9 and more preferably about 6.5to about 7.5. A solvent compatible with the phosphate ester and diamine,can be utilized during the neutralization to facilitate mixing, e.g.,isopropyl alcohol, or a similar alcohol. Reaction temperature canpreferably be within the range of about 60 C. to about 100 F. and morepreferably about 80 F. to about F.

Compositions of this invention are especially useful as corrosioninhibitors in producing oil and gas wells. They are also useful ascorrosion inhibitors in both liquid and gas flow lines, gas-lift wells,pumping operations, and any like operation. The composition may be addedcontinuously by means of a pump, lubricator, etc. to the casingtubingannulus, flow lines, etc. If the casing annulus of a well is blocked,that is, packed off from the tubing, the inhibitor can be added to thetubing; the production is preferably stopped during this type ofaddition. Or, the inhibitor can be added as a solid stick (i.e. thecomposition can be incorporated along with binders, wetting agents, orother compatible agents, e.g. to form a solid article) and placed in thetubing or casing where it melts or dissolves in the well fluids to givethe desired protection to the Well.

In addition, the compositions of this invention can be squeezed into theformation-thereafter the composition is flushed out of the formationwhen the well is produced. The latter method can impart a reasonablylong protection, e.g. 6 to 12 months to the well bore. However, theinvention is not recommended where barium sulfate scale is principallycharacteristic of fouling production.

These compositions are useful to form protective films on any metal.Yellow metals can be coated with the composition to give protectionagainst corrosion, scale, etc. Other metals including carbon steel,stainless steel, etc. can also be eifectively coated with thesecompositions.

The composition is useful in amounts sufiicient to form a mono-molecularlayer on the surface 'of the'metal to be portion of the corrosive orscaling medium is useful to protect equipment, e.g. tubing and casing ina well.

The following examples are presented to teach specific workingembodiments of the invention. These examples are not intended to limitthe invention in any way. Rather, H all equivalents obvious to thoseskilled inthe art are intended to be incorporated into the scope of theinvention as defined in the specification and appended claims. Unlessotherwise specified, all percents are based on weight.

EXAMPLE I CORRATOR READING 100 scale: 10 scale I 20 millivolts 10millivolts The above data were determined after the well was cleaned bybailing, pumped for five days and then the Corrator probe was placed ina flow line. The 100 scale reading indicates a pitting tendency of thusa severe pitting condition is present. The well was treated with 5gallons of an aqueous solution containing 25% tap water, 25%isopropanol, and 50% of a chemical composition obtained by neutralizinga phosphate ester (obtained by reacting equal molar amounts ofpolyphosphoric acid and the condensation product obtained by reacting 1mole of N-butyl alcohol and 1 mole of ethylene oxide) with Duomeen L-ll(a trade name of Armour Industrial Chemicals, Chicago, Ill., identifyingan N-secondary-alkyl trimethylene diamine wherein the alkyl groupcontains an average of about 11 to about 14 carbon atoms) to a pH ofabout 7.0 at 90 F. The resulting mixture contains about equal Weightamounts of the isopropyl alcohol, the reaction product of phosphateester and the Duomeen L- 11 and water. The aqueous solution iscirculated for two hours through the annulus of the Well and through thetubing. A reading on a Corrator placed in a circulating line indicatedthat the corrosion rate was now 0.7 mil per year; the pitting tendencywas drastically reduced, as evidence by the following data:

CORRATOR READING 100 scale: 10 scale millivolts 10 millivolts A:+1.0A:+1.0. B:+2.0 B:+1.2.

The well was placed back on production. After two Weeks of production,the Corrator reading was made again. The corrosion rate calculated fromthe Corrator readings indicated a 0.0 mil per year corrosion rate; Acontinuous check of the corrosion rate within this well indicated that100% corrosion protection is obtained by circulating 5 gallons of thischemical composition for two hours every month.

EXAMPLE II To test the scale inhibition characteristics of thecompositions of this invention, an apparatus was used which comprisesrotating a heated metal rotor in a water solution containing thescale-forming mineral. This test procedure is described in an article byF. W. Jones Chemical 1? 50% isopropanol and 50% of the compositionInhibition of Mineral Scales, presented at The National -Association ofCorrosion Engineers, South Central Region Annual Conference, Tulsa,Okla., October 1960. The heated metal rotor is easily weighed, coated,and cleaned. The rotor assembly is made of tubing and the disk or rotoris perforated metal (sheet metal) welded at the end of the tubing.Cylindrical electrical heaters watt) are mounted inside the rotor tube.The rotor is rotated at a velocity usually equivalent to about 10 feetper minute at the rotor edge. The aqueous liquid containing thescaleforming mineral, 250 milliliters, is contained in a 400 milliliterpyrex glass beaker and a thermometer is extended into the liquid in thebeaker to record the temperature. The compositions of this invention aretested for CaCO scale inhibition at F. in an aqueous solution containingtap water, 3 grams per liter of CaCO 5% by weight of NaCl and the liquidsaturated with C0 The rotors are immersed in the compositions indicatedin Table l for 10 minutes at ambient temperature, are then washed withtape water to remove excess chemical and are then placed in the aqueoussolution and rotated for 4.5 hours at a temperature of F. Thereafter,the rotors are cooled for one half hour and are dried and weighed. Thepercent inhibition against scale adhering to the rotor is determined byweighing a control rotor (not treated with the composition) before andafter scaling, subtracting from this difference the amount of scaleadhered to a test rotor (i.e. a rotor treated with the composition ofthis invention) and dividing this diflerence by the scale adhered to thecontrol rotor. Table 1 contains the composition used to coat the rotorand the percent inhibition against scale:

TABLE 1 Percent inhibition against scale Sample No. Chemical compositionA 50% isopropanol and 50% of the composition obtained by neutralizingthe phosphate ester of Example I to pH of 6.0 with Duomeen L-15 (same asDuomeen L-11 except the alkyl group contains an average of 15-20 carbonatoms). this composition diluted to 20% in Stoddard solvent.

B Same as A except water replaces the Stoddard solvent.

0--" SameasA D Same as A except Duomeen L-ll is substituted for DuomeenL-15 and 1% of the dirnagncsium salt of ethylene diamine tetracetic acidis incorporated into the solution.

E Same as A except Duomeen L-ll is substituted for Duomeen L-15 andneutralized to pH of 7.0 and 1% of a nonionic wetting agent is added tothe solution (reaction product of 1 mole octyl phenol and 15 moles ofethylene oxide).

91 obtained by neutralizing a monophosphate (obtained by reacting equalmolar amounts of polyphosphoric acid and the condensation product of onemole of iso-amyl alcohol and 4.0 moles of ethylene oxide) to a pH of 6.0with composition diluted to 20% with water.

G Same as F except the monophosphate contains 5.1 moles of ethyleneoxide and Duomeen L 15 is substituted for Duomeen L-11 to neutrahze to apH of 7.

What is claimed is: 1. A phosphorous containing compound obtained byneutralizing to a pH of about 5 to about 9a (1) phosphate ester obtainedby reacting about equal molar amounts of polyphosphoric acid (one moleof polyphosphoric acid is defined as one mole of P 0 as present inpolyphosphoric acid) and a condensation product of an aliphatic primaryalcohol, containing about 1 to about 12 carbon atoms per molecule, andabout 1 to about 10 moles of an alkylene oxide containing about 2 toabout 4 carbon atoms per molecule with (2) N-secondary-alkyl alkylenediamine wherein the alkyl group contains an average of from about 7 to aabout 31 carbon atoms, and the alkylene group contains about 2 to about4 carbon atoms. 2. The phosphorous containing compound of claim 1wherein the alcohol contains about 3 to about 6 carbon atoms.

3. The phosphorous containing compound of claim 1 wherein the alcohol isn-butyl alcohol or iso-amyl alcohol.

4. The phosphorous containing compound of claim 1 wherein the alkyleneoxide is ethylene oxide.

5. The phosphorous containing compound of claim 1 wherein about one toabout 5.1 moles of alkylene oxide is condensed with the alcohol.

6. The phosphorous containing compound of claim 1 wherein the alkylgroup of the diamine contains an average of about to about 20 carbonatoms.

7. The phosphorous containing compound of claim 1 wherein the alkylgroup of the diamine contains an average of about to about carbon atoms.

8. The phosphorous containing compound of claim 1 wherein the alkylenegrouping of the diamine contains 3 carbon atoms.

9. The phosphorous containing compound of claim 1 wherein the alkylenegroup of the diamine is trimethylene.

10. The phosphorous containing compound of claim 1 6 wherein thephosphate ester is neutralized at a temperature less than about F.

11. The phosphorous containing compound of claim 1 wherein the phosphateester is neutralized to a pH of about 6.5 to about 7.5.

12. The phosphorous containing compound of claim 1 wherein the phosphateester and the diamine are neutralized in a solvent.

13. The phosphorous containing compound of claim 12 wherein the solventis isopropyl alcohol.

References Cited UNITED STATES PATENTS 2,891,909 6/ 1959 Hughes 260-924X ANTON H. SUTTO, Examiner US. Cl. XlR.

5 3 UNITED STATES PATENT OFFECE CERTIFICATE OF CGRREGTION Patent No. 3,787 533 ,Dated Jan. 22 197 Invent r( A. L83 Larsen It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Col. 2, line 43; Delete 609C and insert 60F.

Table I, "F", line 95: After "6.0 with" insert --Duomeen L-ll, this--Signed and sealed this 21st day of May 1974.

(SEAL) Attest:

EDWARD M.FL:ETCHER,JR. C. MARSHALL DANN Attestlng Officer Commissionerof Patents zg g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent 3, 787 533 ,Dated Jan. 22 197 lnventor( A. Lee Larsen It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Col. 2, linei +3z Delete some and insert 60F.

Table I, "F", line 85: After 6.0 with" insert ---Duomeen L-ll, this--Signed and sealed this 21st day of May 1974.

(SEAL) Attest:

EDWARD M.FLETCHER,,JR. C. MARSHALL DANN Commissioner of PatentsAttesting Officer

